Valve gears with torsion rod springs



April 23, 195' A. J. BUTTERWORTH 8 VALVE GEARS WITH TORSION ROD SPRINGS5 Sheets-Sheet 1 Filed Dec. 11, 1953 VINVVE'NT'ORH ,4 nwaRrH A. J.BUTTERWORTH 2,789,548

VALVE GEARS WITH TORSION ROD SPRINGS April 23, 1957 5 Sheets-Sheet 2Filed Dec 11, 1953 jivvs/vrax Y ,4, (Z BUTTERh/ORTH April 23,- 1957 A.J. BuTi'ERwoRTH 2,789,548

VALVE GEARS WITH TORSION ROD SPRINGS 5 Sheets-Sheet 3 Filed Dec. 11.1955 v April 23, 1957" A: J. BUTTERWORTH 2,789,548

VALVE GEARS WITH TORSION ROD SPRINGS Fi led Dec. 11, 1953 5 Sheets-Sheet4 April 23, 1957 A. J. BUTTERWORTH 2,789,543

VALVE GEARS WITH TORSION ROD' SPRINGS Filed Dec. 11, 1955 5 Sheets-Sheet5 VALVE GEARS WITH TQRSION ROD SPRINGS Archibald James Butterworth,Frirnley, near Aldershot, Hampshire, England Application December 11,N53, Serial No. 398,67 6

Claims priority, application Great Britain December 12, 1952 14 Claims.(Cl. 123-90) This invention relates to valve gear for internalcombustion engines, compressors and the like and of the kind embodying apivotally mounted rocker having one part thereof which engages or isformed with a valve and another part thereof which is engaged by anoperating member, for example by a cam, or by a push rod actuated by acam and tappet. With such an arrangement, difiiculty may be met inobtaining an efficient and reliable working of the mechanism at highoperating speed. One cause of such difliculty is the phenomenon ofsurging in helical valve springs where vibrations of the coils, excitedby resonance with the cam frequency or a multiple there of, causedeflections and stresses beyond those required for the spring to performits function, and the consequent danger of fatigue failure. An object ofthe present invention is to overcome that tendency.

According to this invention, a valve gear of the kind referred to aboveis characterised in that one or more substantially straight torsion rodsis or are attached at one end to the rocker arm, at or close to its axisof pivoting and at the other end to a part secured to a fixed part ofthe mechanism.

The aforesaid torsion rod or rods may be arranged to extend parallel tothe axis of pivoting of the rocker and is or are rigidly connectedthereto, or the rod or rods may extend at an angle to the axis ofpivoting and are connected to the rocker by a universal joint or joints.

Preferably the rocker has an arm extending on either side of its pivotaxis which two arms respectively engage the valve and the operatingmember. With this arrangement the effort required in the case of avertical engine to lift the valve and to lift that arm of the rockerengaging the valve is balanced or nearly balanced dynamically againstthe effort to push down the other arm of the rocker and the tappet andpush rod should the latter parts be employed. The effect of this partialor complete dynamic balance is that, the load on the rocker bearing,when the valve is being closed, is limited to that caused by thedifference between the moments of inertia about the rocker axis of thoseparts of the valve gear which lie on each side of the axis of pivoting.Not only does this reduction in bearing load and consequent frictionreduce the frictional horse power of the engine or compressor as awhole, but it also reduces the normally large margin of spring effortwhich the designer must provide to overcome friction when returning themechanism at high speed, to a very small value.

The invention is particularly applicable to valve gear in which one ofthe arms of the rocker is forked and is arranged to lie within acircumferential groove formed in a part integral with or secured to avalve stem which stem is slidably mounted in a valve guide.

Preferably the part provided with a circumferential groove is adjustableaxially along the valve stem, for example, said part may comprise aninternally threaded sleeve which engages a threaded part of the valvestem, which sleeve is retained in an adjusted position by a lock nut,which also engages the threaded stem.

atet

the locking surfaces of the sleeve and nut may be of conical form.

The axis of pivoting of the rocker is preferably so disposed in relationto the other parts of the valve gear, that when maximum acceleration ofthe valve takes place under the action of the operating member duringopening, the line of thrust imparted by the forked extremity of therocker to said grooved part is parallel to the axis of the valve stem,and perpendicular to the general plane in which the circumferentialgroove lies. In this way, sliding movement under heavy load between therocker and said part is reduced to a minimum, with consequent reductionof wear and side thrust on the valve guide. This arrangement alsoensures that when the contact pressure between the circumferentiallygrooved part and the forked rocker arm, due to the thrust of the springupon return movement of the valve, is the maximum, the line of thrustwill again be at right angles to the general plane of the groove, againminimizing wear. It will also be appreciated with the above arrangementthat the valve is free to rotate on its own axis and is likely to do sounder the random rotational impulses which nearly always occur in suchmechanism, thus distributing wear around the surfaces of thecircumferential groove.

The aforesaid rocker may be formed with journal portions on either sidethereof mounted in hearings in a fixed part of the mechanism, and theaforesaid torsion rod or rods is or are connected to either or both ofsaid journals.

In one form of construction according to the invention, a bore extendsaxially into said rocker at least a part of which bore is provided witha non-circular contour and a torsion rod is arranged to extend into saidbore and has an extremity shaped to interlock with said non circularportion, while the other extremity of the rod is fixed to the outer endof a structure, the inner end of which is attached to a fixed part ofthe mechanism.

In an alternative arrangement the aforesaid bore may be arranged toextend through both said journal portions and at least center part ofthe bore is non-circular in contour, and two torsion rods are providedwhich respectively enter the two journal portions and are shaped attheir inner ends to interlock with the non-circular center portion ofthe bore while the outer end of each of which torsion rods is secured tothe outer end of a structure the inner end of which is attached to afixed part of the mechanism.

In yet a further alternative form of construction at least one of saidjournal portions is provided with an axially extending bore and there issecured in said bore one part of a pivotal joint, the other part ofwhich is secured to Preferably,

one end of a torsion rod which extends outwardly at an angle to the axisof pivoting of the rocker and the outer end of which torsion rod issecured to a structure attached to a fixed part of the mechanism. Thisarrangement is particularly suitable for a multicylinder engine wherethe space between adjacent cylinder heads may not be sufiicient toaccommodate the required length of torsion rod should the torsion rodextend parallel with the axis of rotation of the rocker, whereas by theprovision of a universal joint the torsion rod may be brought clear ofany obstructions on the adjacent cylinder.

The aforesaid structure to which the outer end of the torsion rod isanchored may be arranged either to be torsionally rigid or torsionallyresilient.

In one form of construction the structure may comprise a tubular elementencircling the torsion rod. It will be appreciated that if the walletsuch a tube is made sufiiciently thin and if it is formed from asuitable material it will itself act as a torsion spring and bycontributing to the totaf-defletion required it will permit of the usesince the deflection of such a system for a given stress is in directproportion to its effective length. However V e Figure is an endelevation of the assemblage shown in Figure 9;

Figures 11 and 12 are diagrammatic side elevations of alternative formsof outer torsion rods;

owing to theinherent stiifness ofa tubein torsion and 5 Figure 13 is asimilar View to Figure 2 showing alteiha' the fact that its insidediameter must besufiicientlylarge tive torsion rod assemblag to passtherlargest diameter of the torsion rod which usu- Figure 14 s a similarView to Figlliev3 she-Wing ally"'has an enlarged noncircular endfor'engaging the siOh rod assemblage similar to that'et Figurenoncircular part of the tube, it is difficult to manufacture Figure 15is a section 011 the line 15-15 of Figure a simple tube-which has a lowspring rate as compared 10 Figure 16 is a section 011 the iiI1e 1616 ofFigure with the torsion bar it surrounds; Forlthis reason the Figure 17is a face VieWOf the boss on -the cylinder n contribute a small part ftheitotal defl head which receives theanchor plate for the torsion rodtionn'equired'of the spring system unless it is to be unduly,assemblage;

trait Figure 18 is an endiviewv of the torsion rod assem- One-"of-theobjects of thisinvention'is to provide a hiage With the CoverIem0Ved;aI1d structure 'for attachment-to the outer end "of a torsionFigure 19 1is a section On the line of Figure rod -having a sufircientlylow rate to enable itto contribute Like etei'ehee Hunter 315 Yeiei tolike Parts in the Various a large'partysay half of the'spring effort anddeflection figures of the drawingsrequired to close the valve, whilst atthe same time being Referring) Figures 1 and 2 stem 10 of a Poppetconsiderably shorter in overall length than the torsion 20 Valve slidesin a Valve guide ad has a screw threaded rodgto which it is attachedThis iasttpoint is f impen extension 12 outside the valve guide. Thisextension is tance as in most practical assemblies it is possible to useengaged by all-internally threaded Sleeve 13 formed with a greaterlength f ttosion ted than of the surrounding a circumferentral groove 14and with a hexagonal head torsion tube. The reason for this is that partof the length t The Outer end face of the head is pmihhid with a of thetorsion rod may pass inside the hollow journals Chhlcal of therocker,whereas the inner end of the torsion tube A hexagon lhckhht 16 has achhical Projhchhh which 1-equites to be anchored tO a sttttiontn-y pat-tof the tneeha enters the aforesaid recess. vTheend of the valve ispronistni 011tsiete the dimensional limits of the toekehwheteas vrdedwith a screwdriver slot 17. It will be seen that the. the outer ends ofboth the torsion red and the tube are position of the sleeve 13 at thevalve stem may be adjusted attached't'o One another and s0 occupyapproximately the h rotahhg it hw to the stem and it cah'he lockedstnnettoint along the axis of the assemblage 1n the ad usted position bythe nut 16, during which proc- The" required low rate in the structureto which the 7 e theslot 17 y he gaged by a screwdriver preventing outerend of the torsion rod is attached may be obtained the from rotatingin anumber of dihcetent Ways. As indicated above one r The circumferentialgroove 14 on the sleeve is engaged form of structure to which the outerend of the torsion hy the forked extremity is of a rocker The upper rodis attached may comprise a tubular element encircling and lower iirhacesof the limbs of the fork are so Shapedthe torsion rod and provided witha number of axially as to perm1t the-small degree of rocking movementrelaextending slots Stopping Short of the points of attaehmeht tive tothe srdes of the groove resulting from the pivotal; of the'torsion rodto the outer end-of the tubular element movement of the rocker 19 whenOpening ciosihg ahdtshort of the point of attztehmeht of the tubular thevalve. The dimensions of the groove and of the forked Inent to the fixedpart of the mechanism thereby rendering extremity of the rocker are soselected as to maintain any the tubular element torsionally resilient.Preferably the back. iahhheiweeh the sieeve ahd theiockei as shiah asends. of said slots are rounded. Possible In an alternative form ofconstruction the structure. to Tiihhtiiei ehii'of the iockeiiis providedwith socket which the outer end of a torsion rod is secured comprises. Twhich is engaged by the and of a Push iod 38 which a socket having anoncircular bore which engages the nonis opeiaied Cahi 39 ihihiighhtappeihh" circular endof a torsion rod which socket has attached i ahoimiiiiiype of opeiatihg'caih is used to open the Vhive thereto anumber of rod-like members whichextend along there Wiiihe dowhwaiiipositive acceleration of the torsion rod and are fixed at their innerends to a 3 Valve forf say the .first quarter of itstotalmovernent,base. secured to a fixed part of the mechanism during which time thelower surfaces of the forked ex-" The following iS a description of anumber of emhodh tremlty of the rockerandthe circumferential groovewill. ments of the invention as applied to the valve gear of an beincontact. ,After this accelerationzperiod,the. caminternal:,eotnhustienengine tefetenee being made to the follower .willbev in contact with the .top surface. of the; accompanyingth-awings inWhieh2 cam and ,there will be negative acceleration of the valves:

Figure "1 is a pa t elevation and Part sectiouahviewof, cohimiied by hieioisihii vaive Spiiiig: about to h cylinder head of an engine; tscribed'which negative acceleration rises to a maximum Fight-e 2' is apart Plan and part Sectional View looking value at full. valve lift.During this part-.of the valve. in the direction f the arrow in Figure1; opening period, the upper surfaces of the forkedextremity Figures isa section on the tines Figure 1 of the rocker and. of thecircumferentialgroove will be looking in the direction of the arrows andthrough two in Contact of the cylinder heads of a multicylinder engine;it W be appreciated that by Shiihhiy piopoiiiohihg pignteit is a sectionon the line of Figure 3h the width of thecircumferential groove,and'by'choosing Fig 5 s a Section through one end ottthe journal h asuitablepositionfor the axis of pivoting of'the rocker of a'rockershowing the form of universal joint connection i can be arrangedihat'when there is maximum acciiieiai'i hetweentit and avtorsioh rod;t1on gf.the; parhs during the-valve openingand closing;

Figure. Gets a section on the 1h] 6 of Figure perio causing. eavypressure between the lower faces.

Ft r of the .forked extremity of the rocker and .of .thewcirw. re e 7 1sa Partial sec'lon on the hue 7 eunhtlerential. glroolventhetlirteofthrustis at right angles,

t 0 e genera p anezto' it e groove" and: aralleli with;

Figure 8 is a h h g ahhithihhiiye 'foi'hi 1 the ,axismfithetvalvestern,:where,by sliding ;movernent: attachment between thc'OHt r'end Oftorsloh rod and s between the-.contactingfaces under heavy'loadisreduced pr n e wnesh d to a i ed'p rt oftheensm e; t a minimumiwith aconsequent reductionof wearsandt a slde i h 0f p h assemside ethrustnon.the :valve guides. Similarly it canbe blage-showin'gfan alternatlve wayof mounting theiouter arrangedthat. asv .theuspring pressure.approachesgitszz:

torsionfrods maXimumwalue causinggtherheaviest contact-betweensa theupper faces of the forked extremity of the rocker and of the face of thecircumferential groove, the direction of thrust is again at right anglesto the plane of the groove and parallel to the axis of the valve.

As seen in Figure 2 the rocker 19 is provided at each side thereof witha journal portion 20, each of which journal portions is supported by abearing 21, fixed to a casing 22, within which the rocker is disposedand formed integrally with the top of the cylinder head 23. As will beseen from Figure 1, the casing is closed by a cover plate 24. An axialbore extends through both journal portions 20 and through the centerpart of the rocker and the central part of the bore is formed ahexagonal hole 25 which is engaged by a hexagonal shaped enlarged end 26of a torsion rod 27, which extends outwardly beyond the end of thejournal portion and the outer end of the bearing 21. The outer end ofeach torsion rod is provided with an enlarged head 28 of hexagonalcontour which interengages with a correspondingly shaped socket at theend of a tubular element 29. The inner end of the tubular element isprovided with a flange 30 which abuts a flange 31 on the bearing 21 andthe two flanges are clamped to the casing 22 by a number of screws 32.Each hexagonal head 28 is retained against axial movement in the tubularelement 29 by a small pin 33 which passes through these two parts.

Each of the tubular elements 29 is cut away on either side thereof asindicated at 34 the cut away portions being provided with rounded ends35.

By these means there are provided between the cut away parts two barswhich connect the outer end of each torsion rod 27 to the casing 22which bars act as torsion members thus enabling considerably shortertorsion rod 27 to be employed than would be the case if the tubularmember 29 was not slotted.

The above arrangement of rocker and torsion spring is shown applied toan exhaust valve.

An inlet valve arrangement is shown at the bottom right hand corner ofFigure 1 in which the rocker is controlled by a torsion spring system asshown in Figure 3 of the accompanying drawings. The inlet valve head 9is carried by one arm 41 of the rocker, the other arm 42 of which isdisplaced laterally from the arm 41 and is formed with a socket 43 whichis engaged by a push rod. As in the case of the exhaust valve rocker 19,the inlet rocker 44 is provided with two journal portions 45, 46, thelatter being supported in a bearing 47 formed in a part of the cylinderhead and the former journal 45 being supported in a bearing 48 formed ona closure member 49 extending over a pocket 50 formed in the cylinderhead which closure member 49 is secured in position by suitable screws51. In the case of the left hand cylinder head of the two cylinder headsshown in Figure 3, the journal portions and rocker are formed with anaxially extending bore 52 of hexagonal cross section. Engaging this boreis a hexagonal head 53 formed on one part of a universal joint whichpart is pivotally connected through an intermediate element 54 to thethird element 55 of the universal joint. This latter element is providedwith a hexagonal socket for receiving an enlarged hexagonal head 56formed at the inner end of a torsion rod 57. The outer end of thetorsion rod is provided with another enlarged hexagonal head 58 which isaccommodated in a similarly shaped socket 59. A half circular groove 60is formed in the outer surface of a socket 59 and bent round this grooveis a steel wire so as to form two limbs 61, 62 which extend back towardsthe aforesaid closure member 49 and have their ends bent at right anglesand clamped between the closure member 49 and a flange formed at theinner end of a tubular cover which flange is attached to the closuremember 49 by suitable screws 51. These two wires thus constituteadditional torsion members.

Acover (not shown) may also be providedfor the previously describedassembly for the purpose of preventing leakage of oil and to lessen thedanger of accidental damage of the somewhat delicate parts.

An alternative form of universal joint for connecting the torsion rod 57to the journal portion 45 is shown in Figures 5, 6 and 7. In thisinstance, the end of the torsion rod is flattened at 63, and passesthrough a slot 64 formed in a pin 65 which is rotatable in holes 66formed on opposite sides of the journal portion 45. It will beappreciated with either of the arrangements last described that thetorsion rod may extend in an inclined manner in relation to the axis ofpivoting of the rocker, and therefore, can be brought clear of the partof the adjacent cylinder head in which the other rocker is mounted.

The cylinder head shown to the right of Figure 3 is an end cylinder headand thus the torsion rod 66 controlling its inlet valve can be arrangedcoaxially with the axis of pivoting of the rocker. The rocker in thisinstance is similarly mounted to that last described, but the torsionrod 66 extend to the end of the inner journal portion 46 where it isprovided with an enlarged hexagonal head 67, which engages a similarlyshaped socket formed at the end of the journal portion 46. Thus theextent of projection of the torsion rod from the side of the cylinderhead is less than the overall length of the torsion rod 66. The outerend of the torsion rod is provided with an enlarged hexagonal head 69which engages a similarly shaped socket at the end of the tubularelement 34, in a similar manner to that described in Figures 1 and 2,and as in the previously described construction, the tubular element iscut away at 34 so as to leave two torsion bars 70 of substantiallyrectangular cross section, as shown in Figure 4, connecting the socketportion of the tubular element to a flange 71 at its other end whichflange is secured to the closure member 49.

Figure 8 shows an alternative form of attachment of the wire springs tothe socket 59 which engages the end of the torsion rod 57. In this casea hexagonal hole 72 is blanked or broached in the centre of a steelplate 73, and two circular holes 74 are pierced each side of it, throughwhich the bent over ends of the wires may pass. In this case axiallocation of the torsion bar is obtained by a cross pin 75.

Whereas a single length of wire forming two torsion bars is shown in thedrawing, two or more such wires may be employed, their ends crossing oneanother at the outer extremity of the assemblage, or a plurality ofseparate wires may be attached, for example, by welding or clamping to asocket engaging the end of the torsion rod without the feature of thewire being bent back on itself, and similar means of attachment may beused for the flanged inner ends.

As an alternative to welding or clamping the outer torsion wires ortorsion bars 76, these, as shown in Figures 9 and 10 may themselvesbemade square, hexagonal or serrated at their ends and may be pressed intosuitably shaped holes in the inner and outer end plates, 77, 78, axiallocation being etfected either by the tightness of the fit or by crosspinning at 79.

A further alternative construction is shown in Figure 11 where thesecondary or outer torsion spring or springs is each made up of a numberof thin spring steel laminations 80. In this case it may be desirable toprevent adjacent laminations from chafing against one another, and thismay be achieved by inter-leaving them with short metal strips 81 at eachend leaving a gap between adjacent laminations over their workinglength, or by reducing the thickness of each lamination at 82 except atthe ends where they are restrained or clamped as shown in Figure 12.

In Figures 13 to 19 is shown an arrangement in which three additionaltorsion rods 87 are provided, grouped around the main torsion rod 66.Figure 13 shows a tor- Sio'n rod arrangements'uitablefor controlling anexhaust Valve-operated by a rocker'16 which is mounted in'a similarmanner as that described with reference to Figure 2. Figures 14 to 16'show a similar torsion rod for controlling an inlet valve operated by arocker 42', mounted in a similar way to that described with reference tothe right hand inlet valve shown in Figure 3. Where it is desiredtoprevent ingress of oil, for example to an induction passage, past theoil impregnated porous bushings 47, 105 supporting the rocker shaft 46oil sealing rings 166 of circular or other section may be fitted inrecesses in the bushes the recess in the bushing 47 being closedby ahardened steel washer 107 so that suction of any appreciable amount ofoil is prevented, while at the same time replenishment of theoil-impregnated porous bushings is permitted by percolation through theouter portion of the bushing diametrically outside the oil sealingrings.

The torsion rod arrangement for both the inlet and exhaust valvecomprises a central torsion rod 66 having an enlarged hexagonal shapedhead 67 at one end, which engages a hexagonal bore in the rocker shaftand provided at the other end with an enlarged hexagonal head 69 whichengages a central hexagonal hole 84 in a plate 83. Grouped around thehexagonal hole are three square holesSS, one opposite every second flatof the hexagon. These holes are engaged by the enlarged ends 86 of threesecondary torsion rods 87, which enlarged ends are square in crosssection. The other ends of the secondary torsion rods are also enlargedat 88 and are of square section and engage square'holes in an anchorplate 89 fixed to the closure member 49. The assemblage is encircled bya tubular casing 90 closed at the outer end and having a flange 91 atthe inner end and clamping screws 95 extend through this flange throughthe anchor plate 89 and engage'the closure member 49.

As will be seen from Figure 16 two of the square heads 86 are secured intheir holes 85 by short pins 92 which are introduced into holes formedin the square heads through holes 93 formed in the plate 83, and this iseffected before the introduction of the enlarged hexagonal head 69' ofthe main torsion rod 66 into the hole in the plate 83. The head 86of'the third secondary torsion rod 87 is secured in position in theremaining square hole in the plate 83 by a pin 94 which extends from oneside of the plate completely through the enlarged head 67 of the maintorsion rod 66, and then into the hole in the head 86 of the secondarytorsion rod. This pin 94 may be secured in its'hole by centre-punching,or similarly. Each of theholes in the plate 33 for the pins 92, 94 atone endterminate short of the edge of the plate. As will be seen fromFigure 16 the plate is substantially triangular in shape with roundedcorners which may be supported by the surrounding casing 90. The innerenlarged ends 86 of the torsion rods 87 are held against axial movementin the holes in the anchor plate by means of a circlip 96 which islocated in a groove formed in a spigot 97 on the anchor plate 89 whichgroove intersects each sqnare hole and enters a slot formed in each ofthe square ends 88 of the secondary torsionrods 87.

To provide an accurate means of locating and preloading the torsion bar66, the sunkfacing 98 (see Figare 17) on the cylinder rocker bushing 43has four tapped holes 99 and one dowel hole 100 surrounding the borewhich houses the bushing 48.

A dowel 110 is fitted in this hole (see Figure 18) and engages a hole inthe flange 49' of the bushing 48 and gives an angular location tothebushing 48 when assembled. This aligns four reamed holes 1M in theflange 49"0f the bushingtwith the four tapped holes 99 men-- tionedabove, the reamed holes being slightly larger in diameter than the majordiameter of the tapped holes. The anchor plate 89 of the spring assemblycarries four holes 1ll2 in the same geometric pattern but arranged inhead which carries the outer such an angular relationship to the innerhexagonal end 6" 7 of "the torsion bar 66', assuming the various partsof the torsion spring to be assembled together, that to bring themjintoalignment with the reamed holes 101 in the bearing flange afterinserting the torsion bar 66 into the valve rocker 46 and bringing theanchor plate 89 into contact with the flange 49' of the bushing, willwind up the torsion rod 66 and apply the necessary pro-load to the valvegear, this angle normally being approximately equal to the working angleof the valve rocker.

Two of the holes in the anchor plate 89 may be drilled' or reamed thesame diameter as the reamed holes 101'in the bushing flange, and twoother opposite holes-are countersunk or taper-reamed to an includedangle int his case of 60. A special tool may be engagedwith the twoformer holes permitting a torque to be applied to the spring assemblyand thus aligning the counter-sunk holes with the corresponding holes inthe bushing flange. The tool must be so shaped as to leave accesstothese counter-sunk holes.

Two special screws, 103 (one of which is shown in Figure 19) threaded tosuit' the tapped holes 99 in the cyli'riderhead and having a parallelportion 109 to engage the reamed holes 101 and 60 counter-sunk heads arescrewed into the counter-sunk holes and on being tightened down willpull the assembly firmly together and at the same time complete theaccurate angular location of. the anchor plate '89. The flanged tubularcovei '90' which may be, for example, an aluminium casting, isthenfitted over thespring assembly and two driled or reamed holes in-it arealigned with the remaining holes -inthe anchor plate. Screws 104 arethen passedl-through 'these holes and tightened down to complete theassembly.

1. An engine valve gear comprising a valve operating rocker, a mountingin which said rocker is oscillatably mounted, an operating elementengaging a part of said rocker so as to apply rocking movement to it, asubstantially straight-torsion rod, a connection between one end of thetorsion rod' and rocker, whereby rocking movement rotates said-end, aconnection between the other end of said torsion rod and a partpermanently fixed in relation to s'aid'moun'ting.

-2.--An engine'valve gearcomprising a valve operatingrocker',-'a=mounting in which said rocker is oscillatably mounted, anoperating element engaging a part of said rocker 'soas toapp'lyrockingmovement to it, a substantially' straight torsion rod, aconnection between one end-of' 'the-rodand said rocker whereby rockingmovement rota'tes"saidend, a connection between the other end o'f therod and one part of a torsionally resilient unit, anotherpart of whichunit is permanently fixed in relation-to said-mounting. V V

3'. An engineva'lve gear according to claim 2 whereiirstiid torsion rodis arranged co-axially' with the axis of 'ro'tation of the rocker andwherein said first connection' rigidly secur'es-the rod to the rocker.

4.'An'enginevalve gear according to claim 2 wherein'said torsion rod isarranged to extend at an angle to the" axisof rotationof said'rock'erand wherein the first said connection comprises an'articular joint.

5. Anengine valve gear according to claim 2 where in' saidrocker isprovid'ed with an arm extending on each side thereof, one of which aimsis arranged to be engaged. by the operating element and the other ofwhich is arranged to operate the valve.

6. Ari-engine valvegear according to claim 2 whereinsa-id rockercomprises an arm disposed on each side thereof, one of which arms isengaged by said operating 'element, a valvestem, a connection betweenthe valve'stem and'zsa'ido'ther arm, which connection comprisesaiforkori said'otherarm, a collar axially adjustable along the valve stem,which collar is formed with a circumferential groove into which thelimbs of the fork extend.

7. An engine valve gear azcording to claim 2 wherein said valveoperating rocker is provided with arms extending on each side thereof,one of which arms is engageable by said operating element, a screwthreaded valve stem, a threaded sleeve in engagement with said valvestem and having a conical depression at one end thereof, a lock nutengageable with said stem and having a conical part engageable with saiddepression and which sleeve is provided with a circumferential groove,and the other of which arms on said rocker arm has a forked extremityengageable with said circumferential groove.

8. An engine valve gear comprising a valve operating rocker havingjournal portions extending from either side thereof, a mounting in whichsaid journal portions are oscillatably mounted, an operating elementengaging a part of said rocker, so as to apply rocking movement to it, asubstantially straight torsion rod extending away from each journalportion, a connection between one end of each rod and one of the journalportions whereby rocking movement rotates said end, a connection betweenthe other end of each rod and one part of a torsionaly resilient unit,another part of each of which unit is fixed in relation to saidmounting.

9. An engine valve gear comprising a valve operating rocker, having ahollow journal portion, a mounting in which said journal portion isoscillatably mounted, an operating element engaging a part of saidrocker so as to apply rocking movement to it, a substantially straighttorsion rod, one end of which extends into said hollow journal portion,which end and the bore in the hollow journal portion are provided withinter-engaging noncircular portions whereby rocking movement of therocker rotates said end, a connection between the other end of thetorsion rod and one end of the torsionally resilient unit, the otherpart of which is fixed in relation to said mounting.

10. An engine valve gear comprising a valve operating rocker having ahollow journal portion, a mounting in which said journal portion isoscillatably mounted, an operating element engaging part of said rockerso as to apply rocking movement to it, a substantially straight torsionrod extending from the journal portion at an angle to the rockingmovement, an articular joint one part of which is disposed within thehollow journal portion and interlocks therewith, another part of whichis connected to one end of said torsion rod, a connection between theother end of the rod and one part of a torsionally resilient unit,another part of which is fixed in relation to said mounting.

11. An engine valve gear according to claim 2 wherein the torsionallyresilient unit comprises a tubular element encircling the torsion rod,means for securing one end of the unit to said mounting, means forsecuring the other end of the element to the outer end of the rod, whichtubular element is slotted to render it torsionally resilient.

12. An engine valve gear according to claim 2 but in said torsionallyresilient unit comprises a number of bars extending parallel with theaforesaid torsion rod and wherein the connection between the torsion rodand the unit comprises a head fixed to the end of the torsion rod andextending on either side thereof, and having sockets in which one end ofsaid bars are fixed, and wherein a part fixed in relation to saidmounting is provided with sockets with which the other ends of said barsare fixed.

13. An engine valve gear comprising a valve-operatingrocker, having ahollow journal portion, a mounting in which the journal portion isoscillatably mounted, an operating element engaging a part of saidrocker so as to apply rocking movement to it, a substantially straighttorsion red, one end of which is of hexagonal contour which extends intoand engages a hexagonal socket formed in the hollow journal portion, theother end of which rod is of similar hexagonal contour to the first anda plate having a hexagonal socket engaging said hexagonal end of the rodand having three sockets of square configuration, grouped around the endof the rods, three subsidiary rods extending parallel with the torsionrod, and grouped evenly around it, each of which rods is of circularcross-section and provided with squared ends, one end of each rodengaging a square socket in the plate and the other end of each rodengaging a square socket formed in a part fixed to the mounting.

14. An engine valve gear comprising a valve-operatingrocker having ahollow journal portion, a mounting in which said rocker is oscillatablymounted, 'an operating element engaging a part of said rocker so as toapply rocking movement to it, said mounting having a fiat outer face, abearing in said mounting supporting said journal and having a flangeoverlying said flat outer face, a substantially straight main torsionrod one end of which extends into the bore of the hollow journalportion, which parts are shaped to interlock with one another, a headhaving a socket therein which is engaged by the other end of the rodwhich parts are also arranged to interlock with one another, an anchorplate abutting the outer face of the aforesaid flange, a plurality ofsubsidiary torsion rods grouped around the main torsion rod, sockets insaid head and in the anchor plate engaging the ends of the subsidiarytorsion rods and in interlocking engagement therewith, which flat faceof the mounting is formed with a group of four threaded holes and saidflange and anchor plate are each provided with a similar set of holes,means for registering the holes in said flange with the holes in theflat face and which group of holes in the anchor plate are so disposedin relation to the sockets therein that when said main and auxiliarytorsion rods are unstrained, the holes in the anchor plate are out ofregister with those in the flange and flat face, and thus require therods to be loaded to effect registration, two screws extending throughthe holes in the anchor plate and engaging two of said threaded holes,an outer casing encircling the torsion rod assemblage and having aflange abutting the anchor plate and provided with two holes forregistering with the other two holes in the end of the anchor plate anda flange and screws extending through said holes and engaging the othertwo holes in the flat face of the mounting.

References Cited in the file of this patent UNITED STATES PATENTS1,988,018 Peterson Ian. 15, 1935 2,041,539 Gaultier May 19, 19362,100,057 Krebs Nov. 23, 1937 2,398,207 Chilton Apr. 9, 1946 2,401,480Halliday June 4, 1946 FOREIGN PATENTS 511,272 Great Britain Aug. 15,1939 727,124 Germany Oct. 26, 1942 816,032 Germany Oct. 8, 1951

